Passive ThunderBolt 3 cable (20 Gbps) is sufficient for the ThinkPad ThunderBolt 3 Dock. It will run a 4K display at 60Hz. Active cable not required. : r/thinkpad
Lenovo ThinkPad Thunderbolt 3 Dock Gen 2, EU, 40AN0135EU - EET
Original Lenovo ThinkPad Hybrid USB A/Type C Dual Interface Desktop Multi Dock Adapter 40AF0135CN X1 X390X280T490T480X280| | - AliExpress
Lenovo #ThinkPad Thunderbolt 3 Dock Gen 2 (4K60FPS) - YouTube
Lenovo Thinkpad TBT3 WS Thunderbolt Workstation Cable for Dock 0.7m 03X7540 | eBay
Lenovo ThinkPad Thunderbolt 3 Dock Gen 2, EU, 40AN0135EU - EET